The present invention relates to an improved web winding apparatus, and more specifically, to such an apparatus in which fluid under pressure is used to control deflection of the web as it is wound onto a spool.
Web winding apparatus of various types are well-known in the art. When winding some webs, especially photographic film, care must be taken to avoid scratching the surface of the film since the scratches may be visible after development of images on the film. Thus contact with the film should be avoided to minimize the possibility of scratching the film.
In one prior film winding apparatus the film is advanced along a path leading through a cutting mechanism and between film guides to a spool. After the leading end of the film is attached to the spool, the spool is rotated to wind a number of convolutions of the film onto the spool. Then the film is cut, the wound spool is moved away from the winding apparatus and a new spool is moved into place for winding film onto the spool. The leading end of the film is then driven from the cutting mechanism through the film guides to the new spool for attachment to the spool.
In such prior apparatus the film guides comprise a first guide that extends the full width of the film and is located adjacent one surface of the film, and a pair of movable edge guides located adjacent the opposite surface of the film only in the area along the lateral edges thereof that are outside the normal image area of the film. As the film is wound onto the spool the spool is rotated in a direction which brings the film into contact with the edge guides due to the gradual increase in the diameter of the film on the spool as each new convolution of the film is wound onto the spool. As a result, some scratching of the film can occur on the second surface of the film due to the wiping of that surface against the edge guides. Since the guides only contact the film outside the image area, this does not adversely affect images formed on the film. However, some photographers may notice the scratching in this area and be concerned that some scratching also has occurred in the image area. While the spacing between the fixed guide and the movable guides could be changed to enable the film to be out of contact with the movable guides during winding of film on the spool, this would change the path of the film through the cutting mechanism and cause the film to wipe along an edge of the cutting mechanism, thereby scratching the image area of the film. Accordingly it is desirable to provide an improved web winding apparatus which avoids contact with the film in the area between the cutting mechanism and the spool but which maintains the film path through the cutting mechanism in a plane which avoids scratching of the film in that area, while at the same time enabling the film path near the spool to change in response to the increasing diameter of the film on the spool during winding of film onto the spool.